Characterization of sulfotransferase proteins from Arabidopsis thaliana Von der Naturwissenschaftlichen Fakultät der Gottfried Wilhelm Leibniz Universität Hannover zur Erlangung des Grades Doktorin der Naturwissenschaften Dr. rer. nat. genehmigte Dissertation von Dipl.-Biol. Marion Klein geboren am 07.06.1972 in Rinteln 2007 II Referentin: Prof. Dr. Jutta Papenbrock Korreferent: Prof. Dr. Bernd Huchzermeyer Tag der Promotion: 21.12.2006 III Summary The aim of this study is the characterization of sulfotransferases (SOTs) from Arabidopsis thaliana (L.) Heynh. SOTs are a group of enzymes widely distributed in eubacteria and eukaryotes, but not in archaea. These enzymes catalyze the transfer of a sulfate group from the co-substrate 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to a hydroxyl group of various substrates with parallel formation of 3'-phosphoadenosine 5'-phosphate (PAP). The fully sequenced genome of Arabidopsis was searched for SOT sequences with the already isolated SOT RaR047 protein sequence from Arabidopsis using the BLAST program. Eighteen genes encoding SOTs (AtSOT1 to 18) have been identified and were divided into seven groups according to their sequence similarities. To date, the SOT family of Arabidopsis has to be enlarged by four proteins.